Project 1 - Meshing of Floor Panel

AIM

To Pre-process the given automobile floor panel CAE-ANSA.

GIVEN

• Model in .iges format.
• Quality Criteria for the Shell Mesh: Target Element Length = 5 units.

OBJECTIVES

To pre-process the given Floor Panel by generating mid-surface and meshing using batch meshing method. Setting Property ID, applying thickness and draw shells as solid.

METHODOLOGY/PROCEDURE

1. Import the geometry:

The given .igs model file of the floor panel is imported into ANSA. To get start with the analysis of the given component – for geometry cleanup in a very effective way.

2. Topo:

Topology should be done in-order to stitch the surfaces together. Topo command can be accessed in Topo deck ----> Faces ----> Topo.

3. Geometry Checks:

Geometry checks should be carried out to ensure whether the given surface of the component is out of geometrical errors or issues in the form of extra surfaces, triple cons, needle edges or faces, etc. If error found, it can be fixed by either auto fix option in the ANSA or by manual method. Geometry check command can be accessed in Tool bar ----> Checkup ----> Geometry. However, before geometry check, the surfaces should be inspected for regularity and uniformity. This can be done by either smoothening the surfaces by length perimeter = 1mm or by fine tool. Former method of assigning length perimeter = 1mm is done in the given case and the surfaces are inspected. The command can be accessed by Mesh ----> Perimeters ----> Length ----> Perimeter/Macro = 1mm. The component after assigning perimeter and carrying out geometry checkup are shown in Fig (3) to Fig (5).

4. Thickness measurement:

The thickness should be measured throughout the critical areas of the components as per the geometry demand. However, sheet metal components have uniform thickness while plastic components have non-uniform thickness throughout the component. The command can be accessed in Utilities bar ----> measure. It is up to the engineer’s discretion to measure the thickness with the node or cons or faces options as per the component demands. The components with measured thickness are shown below:

5. Mid-Surfacing:

Mid-surfacing is the process of extracting mid surface of the above sheet metal component in order to simplify the geometry, while entering the thickness manually. This can be accessed by Topo ----> Faces ----> Offset ---->(either a specific face can be selected or window selection can be done depending on the geometry of the component). And thickness is entered manually in the offset window. Property Identity(PID) is manually set. PID can be accessed by Topo ----> Faces ----> Set PID.

The mid-surfacing of the component by offsetting is shown Fig (7).

Geometry check should be carried out again in order to make sure extracted surface is out of any geometrical errors.

6. Assigning Property ID:

Now separate property for the created mid-surface is carried out. The property id can be assigned with the thickness = 1unit. The command can be assessed by Topo ----> Faces ----> Set PID ----> Macros or Shells ----> Selection of component. The entire procedure is pictorially briefed from Fig 9 to Fig 11.

7. Assigning Mesh parameters and Quality Criteria:

Assigning of mesh parameters and quality criterial carried out as shown in Fig (12) and Fig (13).

8. Meshing:

Meshing is done by Batch Meshing as elaborated from Fig 16 to 18. Batch meshing can be accessed by Tools ----> Batch Mesh in the tool bar. Before starting of with the batch mesh, the new PID need to be assigned as new part, so that batch mesh can recognize. For this, the extracted surface is assigned to a new part name in Model Browser. The means to access model browser is Lists ----> Model Browser ----> New Part(right click) ----> Model selection in GUI ----> Floor Panel(Renamed).

Once the new part is assigned for the PID of the extracted surface from now is called as floor panel, close the model browser. Now open the batch mesh located in the tool bar, create new scenario. Load the floor panel under the content, load mesh parameters and quality criteria and hit run. Ansa will create the whole surface meshing in a matter of time. The mesh generated is coarse and should be refined in order to satisfy the criteria of -

1. clearing all Off elements,
2. reducing the trias to a great extent,
3. averting trias concentration; and
4. to channel the mesh flow.

The above listed criteria are carried out by Reconstruction tool or Improve tools or with appropriate tools under Shell Mesh. In parallel, hole features where the floor panel getting mounted to the chassis of the automobile is recognized and given special treatment by sliding the hole to match any side parallel to appropriate mesh flow direction or matching to feature lines if any present nearby. And freezing the end nodes by mark/unmark function. Then zone cut is done. Perimeter is assigned around the zone cut as shown in Fig 20. Then the entire zone is locked/frozen with freeze/unfreeze command.

Reconstruct tool can be accessed by Mesh ----> Shell Mesh ----> Reconstruct(Window Select). Whereas the improve tool has additional improvement features to offer viz., reconstruct, improve, reshape and fix quality. As per the requirement, user can utilize improve tool. To access this tool: Mesh ----> Shell Mesh ----> Improve(Window Select). Make sure that meshed components should not consists of any Offs. Whenever it is demanding use split, swap and join to improve mesh and mesh flow. Split is a hybrid command which is located in: Mesh ----> Elements ----> Split. On the left-click of mouse button, it splits the element with respect to Edges or Nodes or with both as per the user choice. Upon right-click, it works as join or swapping of edges. Care has been taken to a great extent to avoid trias at the free edges or at any feature perimeters to reduce the stress concentration; and rotating quads and opposite trias also avoided in order to get better results. Meshed component is shown in Fig 21.

CONCLUSION

Hence, the given component – Floor Panel of an automobile is meshed after extracting the mid-surface by manual or offset method after fixing geometry issues. The geometry issues of the extracted mid-surface also are fixed. The surface is then meshing as per the mesh parameters governed by the provided quality criteria. After refining the mesh, the thickness is assigned to the meshed component and graphically represented as draw shell as solids in Fig 23.

Learning Outcome

• Hands on experience on ANSA Pre-processor tool. With working experience in Batch meshing.
• Familiarized with ANSA tool while working with the model, which instills much faster working with the ANSA tool in the future challenges.

NOTE: Since I am unable to upload and attach the project’s .ansa file to, I have, hereby uploaded to my google drive and provided the link here. Please check the link for the attachment of .ansa file.

https://drive.google.com/file/d/1Qc07ztQ-GOoG6Zd77-Q98R9QveRVA5ig/view?usp=sharing